Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Carbon exchange of a maize (Zea mays L.) crop: Influence of phenology
    Jans, W.W.P. ; Jacobs, C.M.J. ; Kruijt, B. ; Elbers, J.A. ; Barendse, S.C.A. ; Moors, E.J. - \ 2010
    Agriculture, Ecosystems and Environment 139 (2010)3. - ISSN 0167-8809 - p. 316 - 324.
    netto ecosysteem uitwisseling - koolstofvastlegging - fenologie - rogge - maïs - zea mays - organische meststoffen - nederland - net ecosystem exchange - carbon sequestration - phenology - rye - maize - zea mays - organic fertilizers - netherlands - gross primary production - rain-fed maize - ecosystem respiration - dioxide exchange - eddy covariance - soil respiration - growing-season - use efficiency - united-states - phase-change
    A study was carried out to quantify the carbon budget of a maize (Zea mays L.) crop followed by a rye cover crop in the Netherlands, and to determine the importance of the phenological phases and the fallow phase when modelling the carbon budget. Measurements were made of carbon fluxes, soil respiration, biomass and Plant Area Index (PAI). On the basis of PAI the annual cycle was subdivided into 5 phases: juvenile-vegetative, adult-vegetative, reproductive, senescence and fallow. To model the annual carbon budget, it should be sufficient to assess the light response in the juvenile-vegetative phase, the growing season and the fallow phase, combined with the length of these phases and the PAI development. We conclude that emphasis should be put on determining off-season fluxes while the growing season can be estimated from radiation only. During the cultivation period (from sowing to harvest) 5.97 tC ha−1 was sequestered by the maize crop. The amount of carbon exported from the field was 7.5 tC ha−1, and the estimated amount of carbon imported by organic fertilizer was 0.51 tC ha−1, resulting in a carbon loss of 1.02 tC ha−1 from the soil. The fallow phase, with a rye cover crop at the field, decreased the amount of carbon fixed in the cultivation period by 2.65 tC ha−1 (44% reduction). To enable determination of the carbon sequestration or emission of croplands, farmers should be required to analyze, apart from the nitrogen content, also the carbon content of organic fertilizers.
    A study was carried out to quantify the carbon budget of a maize (Zea mays L) crop followed by a rye cover crop in the Netherlands, and to determine the importance of the phenological phases and the fallow phase when modelling the carbon budget. Measurements were made of carbon fluxes, soil respiration, biomass and Plant Area Index (PAI). On the basis of PAI the annual cycle was subdivided into 5 phases: juvenile-vegetative, adult-vegetative, reproductive, senescence and fallow. To model the annual carbon budget, it should be sufficient to assess the light response in the juvenile-vegetative phase, the growing season and the fallow phase, combined with the length of these phases and the PAI development. We conclude that emphasis should be put on determining off-season fluxes while the growing season can be estimated from radiation only. During the cultivation period (from sowing to harvest) 5.97 tC ha(-1) was sequestered by the maize crop. The amount of carbon exported from the field was 7.5 tC ha(-1), and the estimated amount of carbon imported by organic fertilizer was 0.51 tC ha(-1), resulting in a carbon loss of 1.02 tC ha(-1) from the soil. The fallow phase, with a rye cover crop at the field, decreased the amount of carbon fixed in the cultivation period by 2.65 tC ha(-1) (44% reduction). To enable determination of the carbon sequestration or emission of croplands, farmers should be required to analyze, apart from the nitrogen content, also the carbon content of organic fertilizers. (C) 2010 Elsevier B.V. All rights reserved.
    Variability in carbon exchange of European croplands
    Moors, E.J. ; Jacobs, C.M.J. ; Jans, W.W.P. ; Supit, I. ; Werners, S.E. ; Kutsch, W.L. ; Elbers, J.A. ; Kruijt, B. - \ 2010
    Agriculture, Ecosystems and Environment 139 (2010)3. - ISSN 0167-8809 - p. 325 - 335.
    netto ecosysteem uitwisseling - kooldioxide - emissie - landbouwgrond - gewasproductie - variatie - europa - net ecosystem exchange - carbon dioxide - emission - agricultural land - crop production - variation - europe - agricultural soils - net carbon - sequestration - forests - respiration - ecosystems - fluxes - model
    The estimated net ecosystem exchange (NEE) of CO2 based on measurements at 17 flux sites in Europe for 45 cropping periods showed an average loss of -38 gC m-2 per cropping period. The cropping period is defined as the period after sowing or planting until harvest. The variability taken as the standard deviation of these cropping periods was 251 gC m-2. These numbers do not include lateral inputs such as the carbon content of applied manure, nor the carbon exchange out of the cropping period. Both are expected to have a major effect on the C budget of high energy summer crops such as maize. NEE and gross primary production (GPP) can be estimated by crop net primary production based on inventories of biomass at these sites, independent of species and regions. NEE can also be estimated by the product of photosynthetic capacity and the number of days with the average air temperature >5 °C. Yield measured at these sites or reported at the NUTS2 level dataset of EUROSTAT is a relatively poor predictor of NEE. To investigate the difference in the variability in CO2 emissions of different crops at the same location and to compare this variation with the variation of the same crop at different locations and with the inter-annual variation the measured dataset at the flux sites was extended with simulated data. These simulations show that the variability in carbon exchange is determined by: firstly the choice of crop and the location and to a lesser extent by the yearly differences in climate.
    Latitudinal patterns of magnitude and interannual variability in net ecosystem exchange regulated by biological and environmental variables
    Yuan, W.P. ; Luo, Y.Q. ; Richardson, A.D. ; Oren, R. ; Luyssaert, S. ; Janssens, I.A. ; Ceulemans, R. ; Zhou, X.H. ; Grunwald, T. ; Aubinet, M. ; Berhofer, C. ; Baldocchi, D.D. ; Chen, J.Q. ; Dunn, A.L. ; Deforest, J.L. ; Dragoni, D. ; Goldstein, A.H. ; Moors, E.J. ; Munger, J.W. ; Monson, R.K. ; Suyker, A.E. ; Star, G. ; Scott, R.L. ; Tenhunen, J. ; Verma, S.B. ; Vesala, T. ; Wofsy, S. - \ 2009
    Global Change Biology 15 (2009)12. - ISSN 1354-1013 - p. 2905 - 2920.
    netto ecosysteem uitwisseling - kooldioxide - eddy-covariantie - patronen - ruimtelijke variatie - variatie in de tijd - net ecosystem exchange - carbon dioxide - eddy covariance - patterns - spatial variation - temporal variation - water-vapor exchange - northern temperate grassland - native tallgrass prairie - carbon-dioxide exchange - long-term measurements - plant functional-type - eddy covariance data - deciduous forest - european forests - co2 exchange
    Over the last two and half decades, strong evidence showed that the terrestrial ecosystems are acting as a net sink for atmospheric carbon. However the spatial and temporal patterns of variation in the sink are not well known. In this study, we examined latitudinal patterns of interannual variability (IAV) in net ecosystem exchange (NEE) of CO2 based on 163 site-years of eddy covariance data, from 39 northern-hemisphere research sites located at latitudes ranging from ~29°N to ~64°N. We computed the standard deviation of annual NEE integrals at individual sites to represent absolute interannual variability (AIAV), and the corresponding coefficient of variation as a measure of relative interannual variability (RIAV). Our results showed decreased trends of annual NEE with increasing latitude for both deciduous broadleaf forests and evergreen needleleaf forests. Gross primary production (GPP) explained a significant proportion of the spatial variation of NEE across evergreen needleleaf forests, whereas, across deciduous broadleaf forests, it is ecosystem respiration (Re). In addition, AIAV in GPP and Re increased significantly with latitude in deciduous broadleaf forests, but AIAV in GPP decreased significantly with latitude in evergreen needleleaf forests. Furthermore, RIAV in NEE, GPP, and Re appeared to increase significantly with latitude in deciduous broadleaf forests, but not in evergreen needleleaf forests. Correlation analyses showed air temperature was the primary environmental factor that determined RIAV of NEE in deciduous broadleaf forest across the North American sites, and none of the chosen climatic factors could explain RIAV of NEE in evergreen needleleaf forests. Mean annual NEE significantly increased with latitude in grasslands. Precipitation was dominant environmental factor for the spatial variation of magnitude and IAV in GPP and Re in grasslands.
    Variability of annual CO2 exchange from Dutch grasslands
    Jacobs, C.M.J. ; Jacobs, A.F.G. ; Bosveld, F.C. ; Hendriks, D.M.D. ; Hensen, A. ; Kroon, P. ; Moors, E.J. ; Nol, L. ; Schrier-Uijl, A.P. ; Veenendaal, E.M. - \ 2007
    Biogeosciences 4 (2007)5. - ISSN 1726-4170 - p. 803 - 816.
    netto ecosysteem uitwisseling - kooldioxide - graslanden - nederland - net ecosystem exchange - carbon dioxide - grasslands - netherlands - greenhouse-gas balance - carbon-dioxide - water-vapor - flux densities - annual sums - respiration - temperature - soil - bog
    An intercomparison is made of the Net Ecosystem Exchange of CO2, NEE, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the NEE was determined during at least 10 months per site, using the eddy-covariance (EC) technique, but in different years. The NEE does not include any import or export other than CO2. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition NEE into Gross Primary Production (GPP) and Ecosystem Respiration (Re) and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of NEE, GPP and Re are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002–2005). Land use and management histories are not considered. The estimated annual Re for all individual sites is more or less constant per site and the average for all sites amounts to 1390±30 gC m−2 a−1. The narrow uncertainty band (±2%) reflects the small differences in the mean annual air temperature. The mean annual GPP was estimated to be 1325 g C m−2 a−1, and displays a much higher standard deviation, of ±110 gC m−2 a−1 (8%), which reflects the relatively large variation in annual solar radiation. The mean annual NEE amounts to –65±85 gC m−2 a−1. From two sites, four-year records of CO2 flux were available and analyzed (2002–2005). Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual GPP was estimated to be 171–206 gC m−2 a−1 (8–14%), of annual Re 227–247 gC m−2 a−1 (14–16%) and of annual NEE 176–276 gC m−2 a−1. The inter-site standard deviation was higher for GPP and Re, 534 gC m−2 a−1 (37.3%) and 486 gC m−2 a−1 (34.8%), respectively. However, the inter-site standard deviation of NEE was similar to the interannual one, amounting to 207 gC m−2 a−1. Large differences occur due to soil type. The grasslands on organic (peat) soils show a mean net release of CO2 of 220±90 g C m−2 a−1 while the grasslands on mineral (clay and sand) soils show a mean net uptake of CO2 of 90±90 g C m−2 a−1. If a weighing with the fraction of grassland on organic (20%) and mineral soils (80%) is applied, an average NEE of 28 ±90 g C m−2 a−1 is found. The results from the analysis illustrate the need for regionally specific and spatially explicit CO2 emission estimates from grassland.
    An intercomparison is made of the Net Ecosystem Exchange of CO2, NEE, for eight Dutch grassland sites: four natural grasslands, two production grasslands and two meteorological stations within a rotational grassland region. At all sites the NEE was determined during at least 10 months per site, using the eddy-covariance (EC) technique, but in different years. The NEE does not include any import or export other than CO2. The photosynthesis-light response analysis technique is used along with the respiration-temperature response technique to partition NEE into Gross Primary Production (GPP) and Ecosystem Respiration (R-e) and to obtain the eco-physiological characteristics of the sites at the field scale. Annual sums of NEE, GPPand R-e are then estimated using the fitted response curves with observed radiation and air temperature from a meteorological site in the centre of The Netherlands as drivers. These calculations are carried out for four years (2002-2005). Land use and management histories are not considered. The estimated annual R-e for all individual sites is more or less constant per site and the average for all sites amounts to 1390 +/- 30 gC m(-2) a(-1). The narrow uncertainty band (+/- 2%) reflects the small differences in the mean annual air temperature. The mean annual GPP was estimated to be 1325 g C m(-2) a(-1), and displays a much higher standard deviation, of +/- 110 gC m(-2) a(-1) (8%), which reflects the relatively large variation in annual solar radiation. The mean annual NEE amounts to -65 +/- 85 gC m(-2) a(-1). From two sites, four-year records of CO2 flux were available and analyzed (2002-2005). Using the weather record of 2005 with optimizations from the other years, the standard deviation of annual GPP was estimated to be 171-206 gC m(-2) a(-1) (8-14%), of annual R-e 227-247 gC m(-2) a(-1)(14-16%) and of annual NEE 176-276 gC m(-2) a(-1). The inter-site standard deviation was higher for GPP and R-e, 534 gC m(-2) a(-1) (37.3%) and 486 gC m(-2) a(-1) (34.8%), respectively. However, the inter-site standard deviation of NEE was similar to the interannual one, amounting to 207 gC m-2a-1. Large differences occur due to soil type. The grasslands on organic (peat) soils show a mean net release of CO2 of 220 +/- 90 g C m(-2) a(-1) while the grasslands on mineral (clay and sand) soils show a mean net uptake of CO2 of 90 +/- 90 g C m(-2) a(-1). If a weighing with the fraction of grassland on organic (20%) and mineral soils (80%) is applied, an average NEE of 28 +/- 90 g C m(-2) a(-1) is found. The results from the analysis illustrate the need for regionally specific and spatially explicit CO2 emission estimates from grassland.
    Photosynthesis drives anomalies in net carbon-exchange of pine forests at different latitudes
    Luyssaert, S. ; Janssens, I.A. ; Sulkava, M. ; Papale, D. ; Dolman, A.J. ; Reichstein, M. ; Hollmén, J. ; Martin, J.G. ; Suni, T. ; Vesala, T. ; Loustau, D. ; Law, B.E. ; Moors, E.J. - \ 2007
    Global Change Biology 13 (2007)10. - ISSN 1354-1013 - p. 2110 - 2127.
    netto ecosysteem uitwisseling - kooldioxide - fotosynthese - dennen - bossen - klimaatfactoren - net ecosystem exchange - carbon dioxide - photosynthesis - pines - forests - climatic factors - interannual climate variability - eddy covariance technique - boreal forest - ecosystem respiration - european forests - atmospheric co2 - temperature variability - terrestrial ecosystems - tree photosynthesis - soil respiration
    The growth rate of atmospheric CO2 exhibits large temporal variation that is largely determined by year-to-year fluctuations in land¿atmosphere CO2 fluxes. This land¿atmosphere CO2-flux is driven by large-scale biomass burning and variation in net ecosystem exchange (NEE). Between- and within years, NEE varies due to fluctuations in climate. Studies on climatic influences on inter- and intra-annual variability in gross photosynthesis (GPP) and net carbon uptake in terrestrial ecosystems have shown conflicting results. These conflicts are in part related to differences in methodology and in part to the limited duration of some studies. Here, we introduce an observation-driven methodology that provides insight into the dependence of anomalies in CO2 fluxes on climatic conditions. The methodology was applied on fluxes from a boreal and two temperate pine forests. Annual anomalies in NEE were dominated by anomalies in GPP, which in turn were correlated with incident radiation and vapor pressure deficit (VPD). At all three sites positive anomalies in NEE (a reduced uptake or a stronger source than the daily sites specific long-term average) were observed on summer days characterized by low incident radiation, low VPD and high precipitation. Negative anomalies in NEE occurred mainly on summer days characterized by blue skies and mild temperatures. Our study clearly highlighted the need to use weather patterns rather than single climatic variables to understand anomalous CO2 fluxes. Temperature generally showed little direct effect on anomalies in NEE but became important when the mean daily air temperature exceeded 23 °C. On such days GPP decreased likely because VPD exceeded 2.0 kPa, inhibiting photosynthetic uptake. However, while GPP decreased, the high temperature stimulated respiration, resulting in positive anomalies in NEE. Climatic extremes in summer were more frequent and severe in the South than in the North, and had larger effects in the South because the criteria to inhibit photosynthesis are more often met.
    Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions
    Owen, K.E. ; Tenhunen, J. ; Reichstein, M. ; Wang, Q. ; Falge, E. ; Geyer, R. ; Xiao, X. ; Stoy, P. ; Ammann, C. ; Arain, A. ; Aubinet, M. ; Aurela, M. ; Bernhofer, C. ; Chojnicki, B.H. ; Granier, A. ; Gruenwald, T. ; Hadley, J. ; Heinesch, B. ; Hollinger, D. ; Knohl, A. ; Kutsch, W. ; Lohila, A. ; Meyers, T. ; Moors, E.J. ; Moureaux, C. ; Pilegaard, K. ; Saigusa, N. ; Verma, S. ; Vesala, T. ; Vogel, C. - \ 2007
    Global Change Biology 13 (2007)4. - ISSN 1354-1013 - p. 734 - 760.
    kooldioxide - eddy-covariantie - netto ecosysteem uitwisseling - gewassen - bossen - graslanden - wetlands - carbon dioxide - eddy covariance - net ecosystem exchange - crops - forests - grasslands - wetlands - northern temperate grassland - gross primary production - atmosphere co2 exchange - eddy-covariance measurements - daily canopy photosynthesis - danish beech forest - leaf-area index - rain-fed maize - long-term - process model
    This paper examines long-term eddy covariance data from 18 European and 17 North American and Asian forest, wetland, tundra, grassland, and cropland sites under non-water-stressed conditions with an empirical rectangular hyperbolic light response model and a single layer two light-class carboxylase-based model. Relationships according to ecosystem functional type are demonstrated between empirical and physiological parameters, suggesting linkages between easily estimated parameters and those with greater potential for process interpretation. Relatively sparse documentation of leaf area index dynamics at flux tower sites is found to be a major difficulty in model inversion and flux interpretation. Therefore, a simplification of the physiological model is carried out for a subset of European network sites with extensive ancillary data. The results from these selected sites are used to derive a new parameter and means for comparing empirical and physiologically based methods across all sites, regardless of ancillary data. The results from the European analysis are then compared with results from the other Northern Hemisphere sites and similar relationships for the simplified process-based parameter were found to hold for European, North American, and Asian temperate and boreal climate zones. This parameter is useful for bridging between flux network observations and continental scale spatial simulations of vegetation/atmosphere carbon dioxide exchange
    Seasonal and interannual variability of carbon dioxide and water balances of a grassland
    Jacobs, A.F.G. ; Heusinkveld, B.G. ; Holtslag, A.A.M. - \ 2007
    Climatic Change 82 (2007)1-2. - ISSN 0165-0009 - p. 163 - 177.
    kooldioxide - netto ecosysteem uitwisseling - vegetatie - graslanden - waterbalans - netto ecosysteem koolstofbalans - koolstofvastlegging - seizoenvariatie - carbon dioxide - net ecosystem exchange - vegetation - grasslands - water balance - net ecosystem carbon balance - carbon sequestration - seasonal variation - eddy-correlation - stomatal conductance - boundary-layer - elevated co2 - exchange - vapor - fluxes - ecosystem - budget - land
    There is great international concern over the increase of atmospheric carbon dioxide and its effect on vegetation and climate, and vice versa. Many studies on this issue are based on climate model calculations or indirect satellite observations. In contrast we present a 12-year study (1994¿2005) on the net ecosystem exchange of carbon dioxide (NEE) and precipitation surplus (i.e., precipitation¿evaporation) of a grassland area in the centre of the Netherlands. On basis of direct flux observations and a process-based model we study and quantify the carbon uptake via assimilation and carbon release via soil and plant respiration. It appears that nearly year-round the assimilation term dominates, which indicates an accumulation of carbon dioxide. The mean net carbon uptake for the 12-year period is about 3 tonnes C per hectare, but with a strong seasonal and interannual variability depending on the weather and water budget. This variability may severely hamper the accurate quantification of carbon storage by vegetation in our present climates and its projection for future climates
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